The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system is widely used and considered the standard in guideline development. In GRADE, grades have two components: a two-level representation of the strength of recommendation (strong or weak) and a four-level representation of the quality of the evidence (high, moderate, low, and very low).
Video: Overview of the GRADE approach in guideline development
The Institute of Medicine (IOM) defines clinical practice guidelines (CPGs) as "...statements that include recommendations intended to optimize patient care that are informed by a systematic review of evidence and an assessment of the benefits and harms of alternative care options" [IOM 2011].
Clinical Practice Guidelines are produced by different government agencies or professional organizations at the local, regional or national level. Many guidelines are published, and they vary in quality. Guidelines produced by different organizations may give different recommendations, and some may not be credible. (See more in "Overview of clinical practice guidelines")
Use the following links to learn more about the guideline development process for various governmental and professional organizations:
Institute of Medicine (US). Clinical Practice Guidelines We Can Trust.
Guideline development process ASCO Methodology Manual
Development and Update of the NCCN Guidelines
American College of Physicians
American College of Chest Physicians
SIGN Guideline Methodological Principles
References:
The following tools can help you evaluate the quality of a guideline you're unfamiliar with:
The two articles linked below discuss the implementation of guidelines in providing healthcare:
When using Research Medical Library databases (PubMed or MEDLINE), you can can limit your search to "practice guidelines," which is under "Publication Types (PT)". For other types of practice guidance, you may try terms for "consensus development conference" (PT), "consensus," "position statement," "practice parameter," "appropriate use criteria," "guidance statements" or variations of those terms. More practically, when you search PubMed from the Research Medical Library website, you may simply use the built-in "Practice Guidelines" filter on the right column of the screen to limit your search results to practice guidelines.
Guidelines can be found at the websites of professional organizations. Currently, there is no single search engine that searches all guidelines. You may use this Google custom guideline search engine.